Introduction to aircraft components

There are thousands of designs and ideas about aircraft which have been developed through aviation history. Despite this some main components became permanent in every aircraft dessing. As fix-wing aircrafts are the most common aircrafts they will be the most studied.

Although airplanes are designed for a variety of purposes, most of them have the same major components. The overall characteristics are largely determined by the original design objectives. Most airplane structures include a fuselage, wings, an empennage, landing gear, and a powerplant. There are many other parts as well.

The fuselage includes the cabin and/or cockpit, which contains seats for the occupants and the controls for the airplane. In addition, the fuselage may also provide room for cargo and attachment points for the other major airplane components. Some aircraft utilize an open truss structure. The truss-type fuselage is constructed of steel or aluminum tubing. Strength and rigidity is achieved by welding the tubing together into a series of triangular shapes, called trusses.

The empennage (also called tail) is the rear part of the aircraft. Usually it includes the stabilizers, rudder and elevator as many other components. In fighter jets it may be constructed around the exhaust nozzle, as in some three-engine airplanes (with the third engine in the fuselage). In commercial aircrafts the empennage is built from the cabin pressure-cone and may contain the Flight Data Recorder ("black box"), Cockpit Voice Recorder and the pressure out-flow valve.,,,,,,,,,,,

The wings are airfoils attached to each side of the fuselage and are the main lifting surfaces that support the airplane in flight. There are numerous wing designs, sizes, and shapes used by the various manufacturers. Each fulfills a certain need with respect to the expected performance for the particular airplane. Wings may be attached at the top, middle, or lower portion of the fuselage. These designs are referred to as high-, mid-, and low-wing, respectively. The number of wings can also vary. Airplanes with a single set of wings are referred to as monoplanes, while those with two sets are called biplanes. Many high-wing airplanes have external braces, or wing struts, which transmit the flight and landing loads through the struts to the main fuselage structure. Since the wing struts are usually attached approximately halfway out on the wing, this type of wing structure is called semi-cantilever. A few high-wing and most low-wing airplanes have a full cantilever wing designed to carry the loads without external struts.

As aircraft move in three dimensions we need various control devices to control it. Fix-wing aircrafts have control surfaces for each one of these dimensions. Usually these are placed in the extremes of the aircraft (tail and wings) to get the maximmun strength and response using small moving parts thanks to the lever concept.

Note that an airplane is easier to maneuver as more unstable it is. Stability can be provided by stabilizers and fuselage and wing dessing.

The vertical stabilizer functions with the same principle a wing does, but being symmetrical. It is a main control surface of airplanes (fix-wing aircraft). Obviously, it has a vertical position, usually in the tail of the aircraft. There can be multiple vertical stabilizers (in large aircraft usually).

The vertical stabilizer has a moving part which is called Rudder. This acts as an aileron does in the wing. When it is moved to one or other side it produces a pressure difference over the stabilizer since it's movement is equal to change the angle of attack of this 'wing'.

The rudder controls the Y-axis or Yaw of the plane and it is controlled from the cockpit with the pedals. In a coordinated turn, rudder and ailerons must be coordinated, but you can use rudder only to 'slide' the aircraft.

Some rudders are mixed with elevators in the same control surface, creating V-tail aircraft.

The horizontal stabilizer is the main control surface of the aircraft, mainly of airplanes (fixed-wing aircraft). It functions as a wing does, creating a second point of lift along the fuselage which provides stability to the aircraft in the Z-axis. Its function is not to provide more lift but to control the Pitch of the aircraft (by modifying the angle of attack of the wing). This is thanks to a moving part or parts called Elevators, which act like an aileron, and are controlled by the longitudinal axis of the joystick or wheel.

Obviously, the horizontal stabilizer has a horizontal position, usually in the tail of the aircraft. It can be on top of the vertical stabilizer (T-tail aircraft), or divided in two parts crossing the vertical stabilizer. Some horizontal stabilizers have no elevators but are a whole elevator (mainly in gliders, since it has a better aerodynamic performance). In Canard-configuration planes, the horizontal stabilizer is positioned not in the tail but in the nose of the aircraft (note that its movement to reduce or increase pitch will be inverted from the one it does when it's placed in the tail).

Sometimes, elevators are mixed with rudders in the same control surface, creating V-tail aircraft. It also can be combined with ailerons, mainly in delta-wing planes.

Ailerons are moving surfaces usually placed near the tips of the wings. The function of an aileron is simple, by moving upwards or downwards it modifies the angle of attack of that section of the wing, sinking or lifting it. This change in the aerodynamic is due to the modiffication of relative curve of the airfoil. Note that ailerons are complementary, so if one moves the other will move on the other direction in the same proportion. This improves the effect as one wing is lifted and the other sunk. Ailerons control the X-axis or roll movement of the aircraft.

Ailerons are controled by the pilot form the cockpit, with the lateral axis of the joystick. To make coordinated turns they movement must be combined with rudder in the same direction. In some planes ailerons are just divided elevators, being possible to use the same surface as aileron or elevator (delta-wing airplanes).

As well as speed and pitch (angle of attack), there are some devices which make possible to modify the lift produced by the wing. These act on the aerodynamics of the wing, mainly on the boundary layer.

A slat is a thin airfoil deployed from the leading edge of the wing. This acts as a new little wing, but its objective is not to produce lift but to generate the circulation needed for it. Slat circulation will be opposite to wing circulation reducing the highest speed of the boundary layer. This reduces the maximum lift also, making its distribution along the wing softer, but allowing the boundary layer to detach later (by reducing the adverse pressure generated in the trailing edge).

Usually, slats are used with flaps during take off and landing operations as both produce extra lift at low speed.

Spoilers are not used for generating lift but for reducing it. They are moving surfaces which are placed vertically across the airfoil. This produces the detachment of the boundary layer before than usual as an adverse pressure is generated.

These devices are not very common in piston engine or turboprop airplanes but in turbojet airplanes and gliders.

Spoilers are used mainly after touch down (landing) and rarely used during the decend and approach.Speedbird 19:20, 1 April 2007 (UTC)Saif Arafa

A propeller is a device which transmits power by converting it into thrust for propulsion of a vehicle such as an airplane, ship, or submarine though a fluid such as water or air, by rotating two or more twisted blades about a central shaft, in a manner analogous to rotating a screw through a solid. The blades of a propeller act as rotating wings, and produce force through application of both Bernoulli's principle and Newton's third law, generating a difference in pressure between the forward and rear surfaces of the airfoil-shaped bladesss.

Piston engines are common four-stroke cycle engines Of course they are dessigned in particular for airplanes, so they use aviation gas and have special characteristics, but their function is very similar to a car engine. Transmission of these engines is connected to a propeller so they can provide thrust. full details in this page end to see more option in their websites.

A jet engine produces thrust by compressing air and releasing it through a directed pipe or nozzle. We will study more deeply this subject in Chapter 3, but essentially an aircraft jet engine is composed of an intake chamber or valve, a fan, one or several compressors, a combustion chamber, one or several turbines and an exhaust nozzle.

The process the air suffers through a jet engine begins with the intake and initial compression, a much higher compression, combustion, discharge into turbines and release. It is common to see jet engines with one more step which is to afterburn the mixture while being released.

A TurboProp engine consists in a jet engine which drives a propeller. The result of this is that we have a much more reliable engine than a piston engine (as much as a jet engine) but not as complicated and big as a jet engine since we don't need the jet-blast for generating thrust but the propeller.

Although gyroplanes are designed in a variety of configurations, for the most part the basic components are the same. The minimum components required for a functional gyroplane are an airframe, a powerplant, a rotor system, tail surfaces, and landing gear. An optional component is the wing, which is incorporated into some designs for specific performance objectives.

The airframe provides the structure to which all other components are attached. Airframes may be welded tube, sheet metal, composite, or simply tubes bolted together. A combination of construction methods may also be employed. The airframes with the greatest strength-to-weight ratios are a carbon fiber material or the welded tube structure, which has been in use for a number of years.

The landing gear provides the mobility while on the ground and may be either conventional or tricycle. Conventional gear consists of two main wheels, and one under the tail. The tricycle configuration also uses two mains, with the third wheel under the nose. Early autogyros, and several models of gyroplanes, use conventional gear, while most of the later gyroplanes incorporate tricycle landing gear. As with fixed wing aircraft, the gyroplane landing gear provides the ground mobility not found in most helicopters.

The powerplant provides the thrust necessary for forward flight, and is independent of the rotor system while in flight. While on the ground, the engine may be used as a source of power to prerotate the rotor system. Over the many years of gyroplane development, a wide variety of engine types have been adapted to the gyroplane. Automotive, marine, ATV, and certificated aircraft engines have all been used in various gyroplane designs. Certificated gyroplanes are required to use FAA certificated engines. The cost of a new certificated aircraft engine is greater than the cost of nearly any other new engine. This added cost is the primary reason other types of engines are selected for use in amateur built gyroplanes.

The rotor system provides lift and control for the gyroplane. The fully articulated and semi-rigid teetering rotor systems are the most common. These are explained in-depth in Chapter 5—Main Rotor System. The teeter blade with hub tilt control is most common in homebuilt gyroplanes. This system may also employ a collective control to change the pitch of the rotor blades. With sufficient blade inertia and collective pitch change, jump takeoffs can be accomplished.

Wings may or may not comprise a component of the gyroplane. When used, they provide increased performance, increased storage capacity, and increased stability. Gyroplanes are under development with wings that are capable of almost completely unloading the rotor system and carrying the entire weight of the aircraft. This will allow rotary wing takeoff performance with fixed wing cruise speeds.

The tail surfaces provide stability and control in the pitch and yaw axes. These tail surfaces are similar to an airplane empennage and may be comprised of a fin and rudder, stabilizer and elevator. An aft mounted duct enclosing the propeller and rudder has also been used. Many gyroplanes do not incorporate a horizontal tail surface.

On some gyroplanes, especially those with an enclosed cockpit, the yaw stability is marginal due to the large fuselage side area located ahead of the center of gravity. The additional vertical tail surface necessary to compensate for this instability is difficult to achieve as the confines of the rotor tilt and high landing pitch attitude limits the available area. Some gyroplane designs incorporate multiple vertical stabilizers and rudders to add additional yaw stability.

Airships, hot-air balloons, gliders and other kind of aircraft have specific components in their desings. They can also use airplane components (renamed or non) or even devices wich do the same function but are different. Anyway, all these should be studied.